Cohorts of 3-6 patients receive escalating doses of IDEC-90Y2B8 until the MTD is determined. The MTD is defined as the dose preceding that at which at least 2 of 6 patients experience dose-limiting toxicity. Once the MTD is determined, additional patients are accrued to determine the MTD of this radioimmunotherapy with the addition of the prophylactic cytokines, G-CSF and IL-11.